The present invention relates to a stereoscopic display method of a hologram and its forming method and its stereoscopic display apparatus for performing a stereoscopic display by forming a hologram of a virtual object or an object which actually exists and, more particularly, to a stereoscopic display method of a hologram and its forming method and its stereoscopic display apparatus for performing a natural stereoscopic display by using 2-dimensional images.
A stereoscopic display is a display for enabling a depth and a thickness of a 3-dimensional object to be visually understood. Such a stereoscopic display is largely demanded in the display of structure designed by a CAD or the like, the display of medical images, or the like. A solid image is impressive as compared with a 2-dimensional display and is also used in a display for amusement in an amusement park, a movie, or the like.
Hitherto, various kinds of methods have already been proposed with respect to the stereoscopic display. There is a hologram as a stereoscopic display which can see a solid image without putting special glasses. According to the hologram, an object image is recorded by using the interference operation of the light. With regard to a still object, a color hologram having an enough depth feeling has already been manufactured.
As a method of stereoscopically displaying a virtual object having a 3-dimensional structure formed by the CAD or the like, there is a computer graphics (CG) method. The computer graphics method relates to a technique for calculating a 2-dimensional image when a target is seen from a predetermined direction and for expressing it with a reality in consideration of the reflection or shadow of the light. However, since the computer graphics show a 2-dimensional image, a stereoscopic feeling is insufficient.
An image having a stereoscopic feeling can be displayed by a holographic stereogram method whereby 2-dimensional images which are obtained by seeing an object from various directions on the basis of the 2-dimensional image by the computer graphics are sequentially recorded into stripe-like regions each having a microwidth in the horizontal direction and a width of the screen in the vertical direction by the holographic exposure.
According to the conventional holographic stereogram method, however, the 2-dimensional image is fundamentally seen and the plane with which a focal point of the eyes coincides doesn't coincide with the position of the image which is seen by the parallax of both eyes and recognized. Therefore, it is hard to see the image and such a state becomes a cause of fatigue. Particularly, in case of displaying a deep image, a burden on the eyes increases and such a stereoscopic display is unpreferable. The conventional hologram is inconvenient as a stereoscopic display system because it is recorded on a film-like medium and it takes a time to perform a developing process. Further, the display contents cannot be rewritten.